A new porcine disease has attacked over 5,000 North European pig farms since late 1990. This disease is now called Porcine Reproductive Respiratory Syndrome (PRRS). First identified in Germany in December of 1990, the problem became increasingly critical in the beginning of 1991. In January and February of 1991 the disease spread to The Netherlands and Belgium. Outbreaks have also been reported from Spain.
It is anticipated that the disease will become very costly from an economic standpoint, comparable or even worse than Aujeszky's Disease.
The principal clinical signs in sows are anorexia and late abortion up to day 110 of pregnancy. With piglets a high incidence of stillborn weak piglets in addition to respiratory problems are observed. In fatteners chronic pneumonia and increased mortality occurs.
In order to develop a vaccine to protect pigs against PRRS or to develop a diagnostic method to determine infection in pigs, the causative agent of this disease has to be identified. However, up to now only a few characteristics of the causative agent have been disclosed, such as its viral nature, haemagglutination properties, buoyant density and growth characteristics in vitro (Wensvoort, G. et al., Vet. Quarterly 13, 121-130, 1991).
It is an object of the present invention to provide sufficient and unequivocally identifying characteristics of the new causative agent of PRRS necessary in order to prepare a vaccine and diagnostic test for the causative agent.